Prior art aggregate products are generally controlled mixtures and admixtures of aggregates with a basic Portland cement binder mixed with water. These prior art products have extended curing times running into periods of several days and, in some instances, weeks. This curing time can be shortened by the use of furnaces or kilns in the drying process. Aggregates with cement as the bonding agent without additives have low tensile strength, low compressive strength and generally lack green strength. These strengths can be improved by additives, but the cost is increased. Prior art aggregate products are formed into coherent masses and poured into shapes at block, brick and precast panel installations under controlled conditions. Factory and inventory costs are high in order to keep sufficient quantities on hand to supply the market demand. Other typical deficiencies exhibited by prior art aggregate products are:
1. Though supposed to cure at room temperatures, they have had a lack of ability to rapidly attain stripping strength in molded products.
2. They have a high sensitivity to moisture absorption.
3. They require delicate handling for all green products.
4. Preformed products must be transported to job sites and many times suffer damage en route, causing rescheduling of on-site time schedules.
5. Factory, warehouse, and storage capital expenditures are high due to the necessity of maintaining large inventories.
Resinous binder compositions similar to those employed in the method of the present invention are used in the foundry arts. Foundry molds are made of sand or aggregates having a uniform particle size. The sand or aggregate is held together by a resin binder composition formed of three compounds: a binder, a resin, and a catalyst. Generally, one-half of one percent of resin binder compound to the total weight of the sand or aggregates used is needed in making foundry molds.
Generally, in making foundry molds, the binder is first mixed with the resin and then this mixture is mixed with the sand or aggregates. After the mold is formed, the exterior is sprayed with the catalyst to set the mold. After the mold has been used it is struck a hard blow which shatters the mold and the sand or aggregate reverts to its original form, allowing it to be reused.
Clearly, such methods as used in the foundry art are not suitable for making high, controlled strength building materials such as contemplated in the method of the present invention.